Sizing Die for 30 Cal?

[fls]

I have read several posts on this site pertaining to the process of determining the proper sizing / lube die (I'm using a Lyman 450 sizer lubricator) for shooting 30 cal. boolits. The general consensus is to slug your barrel and perform measurements then using the max. I.D., purchase the die accordingly. The majority opinion suggests a .310 . . . Please correct me if I missed something?

Anyway, I have a 30 cal. rifle barrel manufactured by Hart. Its a AAA grade S.S target barrel. Additionally, I had a conversation with Hart barrels this morning on this subject. They assured me that "slugging" would not be necessary in that the tolerance of their manufacturing process produced barrels that consistently measure .3080 to .3082. Anything outside this would be scrapped. So, if this in fact the case, which sizing die would you purchase? Using pure line-o-type.

[texassako]

I would fit the throat of whatever your chambering is.

[tomon]

I think .309 would work well in a target barrel. It'd seal well, without an excess of swaging down by the barrel. You don't want to over swage and compromise the hardened boolit surface. Cast your boolits at .310, and size to.309.
What caliber are you chambering?

[Outpost75]

To determine the correct bullet diameter for a rifle, the groove diameter of the barrel is NOT the determinant.

INSTEAD you want to measure the throat, or the unrifled portion of the barrel forcing cone or "ball seat" ahead of the case mouth, before the rifling starts. The best way to do this is from a chamber cast or upset throat slug.

Most accurate for measurement purposes and easiest is to upset a throat slug, or as some people call it a "pound cast."
Start with a sized case with DEAD primer in its pocket. The way I do this is to heat the lead pot, then fill the sized case with DEAD primer plugging the flash hole, and generously overflowing the case.

After the lead cools, clean all spilled lead off the case exterior, then file the exposed lead FLUSH to the case mouth.

Take a piece of PURE lead buckshot or short chunk of pure lead wire and drop it into the EMPTY chamber, letting it fall into the throat of its own weight. (With very long throats you can use a longer piece of wire or a SOFT bullet with long bore-riding nose and not a long grooved section).

Insert your lead-filled dummy case and GENTLY tap it into the chamber using a piece of brass rod until you can close the breech. You are using the lead filled dummy case to force the lead slug into the ORIGIN of rifling. In short throated barrels it helps to drive the slug first into the origin of rifling, far enough to chamber the lead dummy behind it, then close the bolt and upset the slug against the lead dummy using a Brownell Squibb Rod threaded onto the end of your cleaning rod.

You don't need to use a hammer, just let the weight of the rod make many light taps of the squibb rod against the slug until you get a clear "ringing" sound. It need go no farther!

What you want to measure is the diameter of the UNRIFLED portion of the chamber forward of the case neck BEFORE the rifling starts! Extract the dummy and GENTLY tap the lead slug out and measure it. THAT is the diameter you want to size your bullets to!

Using Cerrosafe, etc. is more trouble and you then need to compensate for shrinkage, etc.

The upset pure, dead-lead slug is exact and straight forward!

If you forget EVERYTHING you ever read about slugging barrels and simply cast chambers from now on, and get bullets to FIT THE THROAT you will be far happier in the long run.

The limiting factor in safe bullet diameter is neck clearance. You MUST measure the neck diameter of the chamber on the cast. Most chambers have enough clearance ahead of a fired case mouth that a properly upset throat slug will get you a portion of the case mouth and its transition angle to the throat or ball seat, so that you can measure neck diameter at the mouth and throat diameter of the ball seat.

The loaded cartridge neck diameter must not be larger than 0.0015" SMALLER than the chamber cast at that point, to ensure safe expansion for bullet release. This is absolutely essential for custom target barrels which often have tight-necked chambers which require neck-turned cases. As a general rule the largest diameter of cast bullet which chambers and extracts freely, without resistance, will shoot best.

For instance in a .308 Winchester target rifle with .339" tight-necked chamber and using case necks turned to 0.012," maximum bullet diameter is determined by"

[neck (.339")-2(neck wall thickness 0.012)] - 0.0015 = 0.3135" for a "fitted neck" in which fired cases do not require sizing, but bullets will be held by case springback only. For necked sized fixed ammo, subtract another 0.0015" or .312" IF the chamber ball seat is that large. In a new barrel chambered for jacketed bullets, probably not. Min. SAAMI throat as on the pressure test barrel is 0.3105".

Unless you know your throat is smaller, try .310". If the barrel has been fired more than 1500 rounds with full power jacketed loads .311" will be better. If you shot a couple seasons season of highpower with it, .312" will fit just fine.

John Ardito set all of his CBA benchrest records shooting .312" bullets in his .308 Win. and wildcat .30 cal. rifles.

[gwpercle]

Might as well order .308 , .309 , and .310. You never know just exactly what your rifle is going to prefer. If you can only afford one, go with .309. Good a size as any to start with.
I reloaded a 1903-A3 30-06 and a model 94 Winchester 30-30 for years with boolits sized .308. My Lyman Reloading manual said to size both .308...so I did what Lyman recommended , no internet back then, Lyman was my only guide! Then learned that .309 should be better, ordered that size and guess what, made no difference in accuracy or leading...just wasted a few bucks but at least if I need some sized .309 , I'm ready. Also boolits size easier at .309 than .308 and shoot just fine.
Gary

[WALLNUTT]

Try a sized bullet in a fired case. A snug slip fit will be OK.

[EDG]

You already have avoided slugging your barrel.
Now just pick a die and try it. If it does not shoot pick another and another and so on. If nothing ever shoots for you go back and slug your barrel.
No matter what we tell you - the barrel is really what tells you the die is right.


I have read several posts on this site pertaining to the process of determining the proper sizing / lube die (I'm using a Lyman 450 sizer lubricator) for shooting 30 cal. boolits. The general consensus is to slug your barrel and perform measurements then using the max. I.D., purchase the die accordingly. The majority opinion suggests a .310 . . . Please correct me if I missed something?

Anyway, I have a 30 cal. rifle barrel manufactured by Hart. Its a AAA grade S.S target barrel. Additionally, I had a conversation with Hart barrels this morning on this subject. They assured me that "slugging" would not be necessary in that the tolerance of their manufacturing process produced barrels that consistently measure .3080 to .3082. Anything outside this would be scrapped. So, if this in fact the case, which sizing die would you purchase? Using pure line-o-type.

[williamwaco]

I know all the rules and everyone has their favorite method.

I use the KISS method. I keep it as simple as possible.

The simplest rule i know is always start with .311.

In 60 years, i have never found a .30 cal rifle or handgun that would not shoot .311 with excellent results.

[Bjornb]

williamwaco is a wise man.

[JonB_in_Glencoe]

I have read several posts on this site pertaining to the process of determining the proper sizing / lube die (I'm using a Lyman 450 sizer lubricator) for shooting 30 cal. boolits. The general consensus is to slug your barrel and perform measurements then using the max. I.D., purchase the die accordingly. The majority opinion suggests a .310 . . . Please correct me if I missed something?

Anyway, I have a 30 cal. rifle barrel manufactured by Hart. Its a AAA grade S.S target barrel. Additionally, I had a conversation with Hart barrels this morning on this subject. They assured me that "slugging" would not be necessary in that the tolerance of their manufacturing process produced barrels that consistently measure .3080 to .3082. Anything outside this would be scrapped. So, if this in fact the case, which sizing die would you purchase? Using pure line-o-type.
Welcome to the forum.
I'm not sure which mold you are using, but unless you order special oversize molds, most 30 molds I have cast very near .311 or just a little under. So I lube and size them with a .311 die and the boolit is sized very little or not at all. If you gun needs them smaller, then I'd suggest sizing them down with the lee style push through sizer after they have been lubed in your lubesizer. Your gun is gonna tell you what size it wants. Good Luck.